Spatial variability of surface soil water content and its influencing factors on shady and sunny slopes of an alpine meadow on the Qinghai–Tibetan Plateau

Abstract

Soil moisture is a vital factor that influences soil characteristics and vegetation distributions in alpine meadow regions. Previous studies have mainly focused on the effects of alpine gradient change, climate change, and human activities on soil hydrological characteristics and vegetation distributions worldwide. However, the spatial variability of the surface soil water content and its influencing factors between shady and sunny slopes in alpine regions are seldom conducted, especially on the alpine meadow regions of the Qinghai–Tibetan Plateau. Based on soil sample collection, combined with statistical, geostatistical, stepwise regression, and geographical detector analysis, this study explores the spatial variability of the surface soil water content and its influencing factors on the shady and sunny slopes of the Mila Mountain pass area on the Qinghai–Tibetan Plateau. Results show that the average soil water content of various depths ranges from 23.14% to 35.52%. The soil moisture content of different soil layers on the shady and sunny slopes shows moderate variability. On the sunny slope, the spatial distribution of the soil water content in different soil layers is mostly patched and banded, while the soil water content on the shady slope shows patchy distribution. The correlation analysis shows that the soil water content of each soil layer has a very significant correlation (P < 0.01). Stepwise regression analysis shows that the main influencing factors of water content of different soil layers on the shady and sunny slopes are soil physical property indexes. Meanwhile, the vegetation coverage factor has a higher explanatory power except the physical indexes on the shady and sunny slopes. The index interaction detection shows interaction among all the evaluation indexes. On the shady slope, all the interactive combinations of the evaluation indexes in each soil layer shows a double-factor enhanced relationship. On the sunny slope, 60% of the interactive combinations of the evaluation indexes show a double-factor enhancement relationship, but 40% of the interactive combinations show a nonlinear enhancement relationship. This study contributes to knowledge on the variability of surface soil water content and its influencing factors on the shady and sunny slopes in the alpine meadow of the Tibetan Plateau, and provides guidance on artificial vegetation restoration and soil structure analysis in the alpine regions.